Bluetooth low energy (BLE) is currently the most popular radio standard for Internet-of-Things (IoT) applications. IoT nodes are mainly battery operated but increasingly use energy harvesting to sustain their long-term operation. This places heavy emphasis on ultra-low-power (ULP) aspects of IoT Rx, which is considered the most energy-hungry subsystem. Unfortunately, those versatile high-performance RXs developed for the cellular market suffer from relatively high power dissipation, which naturally prevents their use in the emerging IoT applications that take the ULP dissipation and relatively low performance as their starting point.